Rapamycin is one the most use treatment to prevent renal allograft failure. Differently from calcineurin inhibitors (cyclosporine and tacrolimus), that inhibit T-cell activation through the inhibition of calcineurin activation, rapamycin inhibits cellular proliferation by impairing the progression of the cellular cycle, in particular by interaction with mTOR. Recently Battaglia et al. have demonstrated a Treg amplification in murine CD4+ lymphocytes treated with rapamycin in vitro.